An experimental study of Fe-C-Mn-Cr low-carbon steels with varying Cr content is presented. Pronounced bay and a near-stasis behavior were shown in the alloy with 1.1% Cr. Isothermal transformation at temperatures roughly between 500 and 600°C reveals two pronounced stages. SEM examination of the microstructures showed that the rapid first stage is controlled by carbide-free bainite formation while the slow second stage is controlled by a eutectoid-type reaction. Some microstructure features of the transformation were noted and discussed. Based on experimental observations, a model of austenite decomposition was developed to account for the main features of transformation kinetics in the alloys with varying Cr content.